Lubricating oil



Patented Mar. 28, 1944 2,345,239 I LUBRICATING on.

Elmer w. Cook, New Yoran. Y.,

and Philip H. r"

Moss, Greenwich, Conn., assignors ,to American Cyanan id corporation ofMaine Company, New York, N. Y., a

' No Drawing. Application August 28, 19.43,

Serial No. 500,426

6 Claims.

This invention relates to lubricating oils; more particularly tolubricating oils having anticorrosion and detergent properties.

It is now generally known in the lubricating oil art that ordinarylubricating oils, either conventionally refined or solvent refined andof either naphthenic or paraflin base stocks, tend to decompose at highoperating temperatures to form corrosive decomposition products whichattack certain types of alloy bearings. Many different types and kindsof film-forming and anticorrosion agents have been added to lubricatingoils to prevent theformation of these corrosive decom-' positionproducts or to inhibit their attack on the metal surface with which theycome in contact.

It is also generally known that lubricating oils intended for heavy dutyservice in modern types of internal combustion engines require more thanimproved corrosion resistance. Under severe service conditionsthedecomposition products which form in ordinary lubricating oils tend topolymerize to yield resin-like bodies which form sludge and build uplacquer-like deposits on the cylinder walls and pistons of the engine,thus decreasing its efiiciency or even stopping its operationaltogether. Various types and kinds of compounds having detergentproperties have been added to lubricating oils to disperse the sludgeand prevent its deposition on parts of the engine.

The addition of both a corrosion-inhibitor and a detergent to thelubricating oil is not always successful because the two agents aresometimes incompatible and work against each other. Compounds have alsobeen added to lubricating oils which possess both anticorrosion anddetergent properties. However, such compounds are not always availableand may be either too weak in their anticorrosion or detergentproperties to make the oil satisfactory for. heavy duty service.

We have discovered that the compounds to be described hereinafterpossess excellent corrosion inhibiting properties and at the same timepossess mild detergent properties when dissolved in Inbricating oils.These compounds are particularly advantageous for use in lubricatingoils because of their compatibility with other types of compounds thathave good detergent properties but are somewhat lacking in I corrosioninhibiting properties, particularly when leaded fuels are used.Apparently combustion of leaded fuels which contain ethylene dichlorideand ethyl bromide along with the lead tetraethyl produce hydrochloricand hydrobromic acid on combustion and our amine type productsneutralize these .anticorro'sion and detergent properties. The

compounds to be described herein are highly oil soluble and may also beemployed to dissolve more difiicultly oil soluble compounds inlubricating oils.

The compounds which we add to our lubricating oil are new compounds.Their general formula is as follows: I

III!

in which one radicals of from about 1 to 20 carbon atoms, R',

and R"" are short chain alkyl groups and n is the'integer 1 or 2.

In these compounds the total number of carbon atoms in R and R" does notordinarily exceed about twenty since the presence of extremely longchain alkyl groups tends to decrease the oil solubility of the compound.Accordingly, if R or R" is hydrogen, the alkyl group may be anywherefrom 1 to 20 carbon atoms in length, preferably 8 to 14. If both R? andR? are alkyl groups then the total number of carbon atoms in the two ispreferably within the range of about 8 to 14, not usually over about 20.As indicated by the formula above,

NR"'R"" group may have any unoccupied position on the benzene ring.

The above compounds may be prepared by reacting an alkyl phenol with adi-N-substituted aniline and sulfur chloride or sulfur dichloride.Suitable alkyl phenols include 2,4-diamylphenol, p-tertiary-octylphenol,p-tertiary-butyl-o-cresol, 2,4-ditertiary-octylphenol, p-dodecylphenol,and others having one or two alkyl groups of from 1 to 20 carbon atoms.Suitable di-N-substituted anilines include; dimethylaniline,methylethylaniline, diethylaniline, dipropylaniline, methylbutylaniline,and others having alkyl groups up to about 5 carbon atoms in length.

The alkyl phenol and di-N-substituted aniline are joined by a sulfurgroup as shown in thegen-- er l formula. To join the two benzene ringsthe -OH group and with a single sulfur atom, sulfur dichloride isemployed. When sulfur chloride is used the benzene rings are linked bytwo sulfur atoms.

Ordinarily, the reaction is carried out with the alkyl phenol anddi-N-substituted aniline dissolved in a chlorinated solvent such asethylene dichloride trichloroethylene, carbon tetrachloride, chloroform,such as carbon disulfide. The reaction is brought about by merely addingthe sulfur chloride or sulfur dichloride to the solution at temperaturespreferably below room temperature. The reaction is exothermic and it isgenerally advisable to surround the reaction vessel with a coolant suchas ice water. After the sulfur chloride or sulfur dichloride has beenadded the reaction mixture is allowed to stand for a few hours until thereaction is complete. During the reaction, hydrogen chloride is formedand part is retained as the amine hydrochloride, the rest being evolved.The-reaction is substantially complete when hydrogen chloride is nolonger evolved.

To recover the reaction product, the reaction mixture may be treatedwith a dilute solution of a mild alkali to neutralize the hydrochloricacid in the reaction mixture and free the amine compound from its salt.After washing, the aqueous fraction is discarded and the solventfraction evaporated to obtain the product. When the compounds are to be'blended directly in lubricat ing oils, 9. part of the lubricating oilmay be added to the solvent fraction and the excess solvent evaporatedaway. 'Other lubricating oil additives may be added to the mixture atthis time if desired.

Although the compounds may be used directly as prepared by the methodjust described, they may also be used in the form of their metal salts.

' Some of the metal salts of these compounds, particularly the alkalineearth metal salts, have improved detergent properties. These metal saltsmay be made by merely adding a metal hydroxide, such as bariumhydroxide, calcium hydroxide, sodium hydroxide, etc. to the reactionmixture after the compound has been formed and heating it to remove thewater of reaction. Other metal salts may be prepared by treating thefree amino compound with powdered aluminum metal, magnesium turnings,calcium metal, etc. or by heating with an alcoholate of a low boilingalcohol such as methanol. The metal salts may also be prepared bymethods of double decomposition as by heating the sodium salt with asalt such as zinc chloride, aluminum sulfate, copper nitrate, etc.

Since the compounds described herein are new the preparation of a numberof representative compounds of the group, and metal salts thereof, isgiven in the following examples. It should be understood, however, thatthese examples are given primarily by way of illustration and are notintended to limit our invention to the use of the particular compoundsdescribed.

EXAMPLE 1 2-hydroa:y-3,5-di-tert-amyl-4-diethylaminodiphenyl disulflde Asolution of '15 parts by weight of diethylaniline and 120 parts byweight of 2,4-diamylphenol in 240 parts by weight of ethylene dichloridewas stirred in a flask cooled to C. by an ice-water bath. To this liquidwas added slowly '74 parts by weight of sulfur monochloride, thetemperature in the flask being kept below C. When all the sulfurmonochloride was added, the prodetc. or other suitable solvent uct waslet stand 12 hours at room temperature and then treated with sodiumcarbonate solution. The aqueous fraction was discarded and the ethylenedichloride layer washed a second time with sodium carbonate solution.Addition of .nbutyl alcohol assisted in giving a good separation intotwo layers. The product was added to 225 parts of S. A. E. #10 oil,vacuum-dried with a final temperature of 120 C., and filtered, giving aclear, oil-soluble, oil solution of Z-hydroxy- 3,5-di-tert-amylphenyl-4'dlethylaminodiphenyl-disulfide.

EXAMPLE 2 2-hydroxy-3,5-di-terf-amyl-4-dimethylaminodiphenyl disulfideInto 61 parts by weight of dimethylaniline and 120 parts by weight ofZA-diamylphenol in 240 parts by weight of ethylenedichloride was droppedwith stirring 74 parts by weight of sulfur monochloride, externalcooling being employed to prevent the temperature from rising above 20C. When the addition was complete, the product was stirred two hours atroom temperature and then washed twice with sodium carbonate solution. Alittle n-butyl alcohol was added to prevent emul sion formation. Theethylene dichloride solution was dissolved in 200 parts by weight of S.A. E. #10 oil and vacuum-dried with a final temperature of 120 C. Theproduct was filtered to remove a small' amount of inorganic material,giving a clear, oil-soluble, 50% oil solution of 2- hydroxy 3,5tert-amyl 4' dimethylaminodiphenyl disulflde.

EXAMPLE 3 2-hydro:cy-5-tert-octyl-4'-dimethyla1izinophenyl disulfidecooling. After the ethylene chloride solution was twice washed withsodium carbonate solution it was added to parts by weight of S. A. E.#10 -oil and the solvents removed by vacuum distillation. The productwas filtered to remove a slight inorganic precipitate, giving a 50% oilsolution of the 2-'hydroxy-5-tert-octyl-4'-dimethylaminodiphenyldisulfide.

EXAMPLE 4 Z-hydromy 3 methyl-S-tefl-butyl-f-dimethylaminodiphenyldisulflde To 82 parts by weight of p-tert-butyl-o-cresol and 61 parts byweight of dimethylaniline, stirred in 240 parts by weight of ethylenedichloride below 20 C. was added slowly 74 parts by weight of sulfurmonochloride. The reaction mixture remained at room temperature for 16hours and was then washed twice with sodium carbonate solution. A smallamount of n-butyl alcohol aided in breaking the emulsion formed duringthe washing. The ethylene dichloride solution was mixed with 170 partsby weight of S. A. E. #10 oil and vacuum-dried at C. to remove thesolvents. The material was filtered. removing small amounts of sodiumcarbonate and sodium chloride, giving a clear 50% solution aminodiphenyl'Solvesso was replaced as chloride layer was added to t2-hydroxy-3-methyl-5-tert-butyl-4'-dimethyldisulflde in oil.

EXAMPLE Barium salt of 2memory-3,5-di tert-amyl4'- diethyldiphenyldisulflde stirred in an oil bath at 130-140" C. and Solvesso #1 (toluolpetroleum fraction) was added. The it boiled oil until finally all butylalcohol and water had been evaporated. The mixture was filtered and theSolvesso #1 removed in vacuo to give mately 50% oil solution of thebarium salt of 2- hydroxy 3,5 ditert-amyl-4'-diethylaminodiphenyldisulfide.

EXAMPLE 6 salt of 2-hydr0:n1l-3,5-di-tert-amyl-4'- dimethylaminodiphenyldisulflde To 78 parts by weight of a 50% oil solution of Bqrium2-hydroxy-3,5-di-tert-amyl-4'-dimethylaminodiphenyl disulfide was addedan equal volume of n-butyl alcohol and 12 parts by weight of bariumhydroxide. This mixture was stirred at 140 C.

and Solvesso #1 was added to replace the alcohol as it evaporated. Whenall water and butyl alcohol had evolved, the mixture was' filteredthrough Hyfio and vacuum-dried to remove the Solvesso, giving an oilsolution of the barium salt of Z-hydroxy-3,5-di-tert-amyl-4'dimethylaminodiphenyl disulfide.

EXAMPLE '7 2' amet-3,5ea en-newt!.diem zammoai phenyl disulfide In 275parts by weight of ethylene dichloride were mixed 159 parts by weight of2,4-di-tertoctylphenol and '15 parts by weight of diethylaniline. Thissolution was cooled in an icewater bath and stirred during the dropwiseaddition of 70 parts by weight of sulfur monochloride, the reactiontemperature being kept below 20 C. After the mixture had stoodseveralhours it was treated with sodium carbonate solution, separated andwashed again. The ethylene di- 275 parts by weight of S. A. E. oil andall solvents removed by drying in vacuo at 120 C. The residue wasfilteredto give a clear 50% oil solution of 2-hydroxy-3',5-di-tertoctyl-4-diethylam.inodiphenyl To 131 parts by weight of p-dodecylphenoland 75 parts by weight of diethylaniline in 250 parts by weight ofethylene dichloride was added slowly 70 parts by weight of sulfurmonochloride. External cooling was necessary to keep the reactiontemperature below 20 C. The mixture stood overnight before being twicewashed by a solution of sodium carbonate. Addition of n-butyl alcoholduring the washing facilitated separation into twolayers. The ethylenedichloride solution was combined with 240 parts by weight, of S. A. E.#10 oil, vacuum-dried at 120 C. and filtered, giving a clear 50% oilsolution or 2-hya clear, brown, approxistri and the bearing for tenhours.

droxy-5-dodecyl-4'-diethylaminodiphenyl disulfide.

. EXAMPLE 9 of S. A. E. #10 oil,-vacuum-dried at C." and filtered togive a 50% solution of 2-hydroxy-3,5-di-tert-amyl-4'-dimethylaminodiphenyl sulfide.

In most of the above examples the compound was prepared in a 50% oilsolution. This method of preparation is advantageous in that the productis easily handled and can be stored, sold and shipped in this form.Blending with lubricating oils is also greatly facilitated.

The amount of additive employed in our im- 'proved lubricating oils mayvary from about 0.1

to 5% by weight based on the weight of the compounds in the lubricatingoil.

To illustrate the eilectiveness of these new "compounds in preventingcorrosion of alloy bearings by lubricating oils, a copper-lead alloybearing was attached to a copper strip and a Mid- Continent, solventrefined S. A. E. #30 grade oil heated to 325 F. was sprayed against thecopper At the end of the test, it was found that the copper-lead bearingwas corroded and that the neutralization number of the oil was greatlyincreased. Other tests using the same oil with small amounts of the newcompounds added thereto were also made. The results of these tests aresummarized in the following table.

Corrosion,

Coneen- Additive nation 5 hr. 10 br..

Other tests, oil in different types of internal combustion engines, havealso been made and have shown that the compounds described in thepreceding examples are effective in preventing corrosion of alloybearings by'the oil. Theseetests have also shown that the abovecompounds have detergent propertieswhen dissolved in lubricating oils.

We claim:

1. A lubricating oil composition comprising a predominating amount ofmineral lubricating oil and an effective amount of a compound of thegroup consisting of those having the general formula:

in which R and R" are radicals of the group consisting of hydrogen andalkyl radicals at least one being an alkyl radical, R' and R"" are alkylradicals of from 1 to 5 carbon atoms inclusive, and n is a small wholenumber not greater than 2, and the metal salts of such compounds.

2. A lubricating oil composition comprising a predominating amount oflubricating oil and 0.1 to 5% by weight, based on the amount oflubricating oil present therein of a compound of the group consisting ofthose having the general formula I in which R. and R" are members of thegroup consisting of hydrogen and alkyl radicals at least one being analkyl radical of not more than 20 carbon atoms, R' and R"" are alkylradicals of from 1 to 5 carbon atoms inclusive, and n is a small wholenumber not greater than 2, and the metal salts of such compounds.

3. A lubricating oil composition comprising a predominating amount of alubricating oil and 0.1 to 5% by weight, based on the amount oflubricating oil present therein, of a compound of the group consistingof those having the general formula:

in which R and R" are alkyl radicals having a total of not more thanabout 20 carbon atoms, R' and R"" are alkyl radicals of from 1 to 5carbon atoms inclusive, and n is a small whole number not greater than2, and the metal salts of such compounds.

lubricating oil present therein, of 2-hydroxy-3,5-

di-tertiaryamyl-'-dimethyldipheny1 sulfide.

ELMER W. COOK. PHILIP H. MOSS.

